Several years ago I began obsessively making lasagna. Not the dish that is baked in the oven, but one I assembled on my wedge of hardscrabble front garden and baked in the sun.
Adapting a recipe I borrowed from indigenous farmers around the globe, my version of soil lasagna calls for layers of animal manure alternating with a neighbourhood’s worth of flattened pizza boxes, discarded newspaper, and fallen leaves.
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I began this strange project after weeks of staring helplessly at DrawDown.org’s 100 solutions to reduce greenhouse gas emissions and fight Climate Change.
I first visited the site in an attempt to manage my mounting “eco-anxiety” and to help similarly afflicted patients in my medical practice, but the top five actions that DrawDown recommends – build wind turbines, eliminate HFC-based air conditioning, reduce food waste, eat a plant-based diet, and restore rainforests – seemed either unachievable for an individual or did not offer tangible short-term results.
I wanted an action that might produce measurable climate benefits almost immediately, would require few resources, and could happen in my own neighbourhood.
And that’s when I started to wonder what it would take to convert my sloped front garden, with its one balding Camelia bush, into a tropical rainforest – or at least a densely planted tree canopy with lots of flora and fauna thriving beneath. I was not so delusional that I thought this minuscule effort in my part of the world (Northern California) could offset the millions of acres of rainforest in Asia and South America that are chopped down each year. Still, I was hoping to design a living, breathing carbon sink.
But then I realised that anything approximating a rainforest needs really vibrant soil and all I had was hardpacked clay. So that is why I began making soil lasagna.
In his book Gaia’s Garden, a guide to home scale permaculture, Toby Hemenway claims that soil lasagna (or sheet mulching, as he calls it) can swiftly transform lifeless dirt into carbon and mineral-rich soil, “exploding with worms”.
I only half believed him but still, much to my neighbour’s dismay, I began blanketing my sad garden with cardboard boxes.
Amazingly, within six weeks of completing the lasagna, I pushed my shovel deep into a spot that previously had the consistency of concrete, and easily scooped up a huge mound of moist, dark earth, practically vibrating from the macro and micro life within. I kept digging and still did not hit hard clay. Somehow those subterranean creatures had magically appeared to hold on to carbon, minerals, and water, aerate the earth, and nourish the roots of plants. They were converting dirt to soil.
That winter, and into the next spring, I began planting in three layers to imitate a natural forest ecosystem: trees, shrubs and low plants. Within months, the animals moved in; first the butterflies, then the birds and even a little red fox. And the population of soil-dwellers exploded.
I am now in Season Two of “Operation Lasagna”; the trees are filling out and some of the bushes have started to bear fruit. And what my neighbours and I have realised is that, in addition to functioning as a carbon-catching forest, this front-garden zone actually addresses the other priority actions on DrawDown’s list: it offers delicious shade (no need for air conditioning), it recycles paper, garden, and food waste into more food (no energy needed for food transport, trips to the shops or bin collection), and it pumps out a lot of berries, herbs, fruits, nuts, and vegetables (plant-based diet).
And there are even more health benefits that come from building healthy soil and a diverse food forest – even if it’s a really small forest.
Results from an Irish study, along with similar experiments, suggest that growing food in organic, microbially-rich soil increases the vitamin and antioxidant concentration of the plants.
Jill Litt, a researcher in Colorado, found that planting food next to pavements and in front gardens, strengthens neighbourhoods and builds what she calls “collective efficacy”.
Researchers in Europe and the US have found that letting children play in healthy soil and on farms trains their immune system to be less hyper-reactive. This exposure decreases their likelihood of starting on what immunologists call “the atopic march” – from eczema to allergies to asthma.
And one specific type of microbe, isolated from healthy soil, seems to trigger nerve pathways that improve mood and promote a sense of wellbeing.
This last detail might explain why my eco-anxiety is under better control these days. Another reason might be that I am noticing rainforest-inspired gardens and fields popping up in lots of places – from schools and community gardens to small and mid-size farms. There are still millions of acres that need to be saved or restored, but it’s a start.
And for those of you who continue to toss and turn from eco-anxiety, I am sharing my favourite soil lasagna prescription. To get started, please collect two discarded pizza boxes and call me in the morning…
- Daphne Miller MD is clinical professor of family & community medicine at the University of California, San Francisco. Her book ‘Farmacology: Total health from the Ground Up’ is published by Harper Collins
How to make Daphne’s soil lasagna
Ingredients
A pile of well-rotted organic manure from a local farm
A smaller pile of compost from your local nursery or your own heap
Discarded cardboard boxes and newspapers (all tape removed)
Many bags of your neighbourhood leaves – avoid eucalyptus
Water – ad lib
Method
Assemble the following on existing lawn in layers with a thorough drenching between each layer. No need to pull up grass or weeds.
2-3 inches of manure
half-inch cardboard, edges overlapping
1 foot of softly packed leaves
And then
Repeat 2-3 times and top with 2-3 inches of compost and a thin frosting of leaves.
Wait 1-3 months and then plant.
Add leaves and compost as needed annually.
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